Ditching performance of silent aircraft SAX-40 in hybrid wing-body configuration

The planned ditching of aircraft SAX-40 on calm water is numerically simulated to investigate the ditching performance of the hybrid wing-body configuration. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations and the Realizable κ-ε turbulence model are solved by a fluent solver. The relative motion between the aircraft and water is handled by the dynamic mesh method. The air-water interface is tracked by a volume of fluid (VOF) model. During the ditching process, the impact brings about the positive pressure peak on the aircraft's lower surface near the waterline; and the planning brings forth the negative pressure on the aft curved portion of the aircraft's lower surface, resulting in a suck force and a strong nose-up pitch motion. As the aircraft touches the water, the normal load increases rapidly to 2.87G, and the longitudinal load to 1.05G. The slamming pressure reaches a peak of about 720 kPa. This airplane bounces up from the water and this defective performance should be considered during the design of a hybrid wing-body configuration.